Viewing Thenight Skyt HroughBinoculars

7/27/2019 Viewing Thenight Skyt HroughBinoculars

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By Michael E. Bakich

618213 A supplement toAstronomymagazine

ViewingtheNight Skythrough

Binoculars

2009 Kalmbach Publishing Co. This material may not be reproduced in any formwithout permission from the publisher. www.Astronomy.com


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ome amateur astronomers on-sider inoulars an aessory, utmany regard them as a neessity.Ive written often that a egin-

ning amateur should purhase inoularsfirst to view the sky. If your interest inastronomy ontinues, then upgrade to atelesope. Most of the advaned oserv-ers I know own several inoulars.

In some ways, inoulars may e a

etter hoie than a telesope, espeiallyfor those starting out in astronomy. Bin-oulars have a wide field of view and pro-vide right-side-up images, makingojets easy to find. They require noeffort or expertise to set up just slingthem around your nek, step outside, andyoure ready to go. That portaility alsomakes inoulars ideal for those learnights in the middle of the week whenyou dont have the time or inlination toset up a telesope. And, for most people,

oserving with two eyes open rather thanone seems more natural and omfortale.Also, inoulars are easier on your

wallet. Unless youre onsidering image-stailized models, inoulars offer amore affordale way to tour the sky thana telesope. If youre a parent hoping tofoster a hilds interest in the universe,inoulars are a good first step. Even ifthe appeal of stargazing eventually wanes,inoulars an e used for more down-to-earth pursuits.

In ommon usage, you may hear

someone refer to inoulars as a pair ofinoulars. This isnt aurate. The unitis simply inoulars. Tehnially speak-ing, I suppose you ould refer to them asa pair of monoulars, ut youll neveratually hear that.

The numbersEvery inoular has a two-numer desig-nation, suh as 7x50. The first numer(in this ase, 7) is the magnifiation(power). The seond numer (50) is the

diameter in millimeters of eah of theojetive lenses.

This example, 7x50, is the inoular Ireommend as a first unit for oserving.A magnifiation of 7 is in the mediumrange, just high enough to ring outsome detail in large astronomial ojets.

Using too high a magnifiation willover-magnify involuntary motions ofyour hands. That motion auses elestialojets to move around in the field ofview. A high magnifiation also limits thefield of view, making ojets more dif-fiult to find for eginners.

Most advaned amateur astronomersan hold inoulars up to 16x for short

intervals. Also, inoulars with higherpower (like a telesope with a shorterfoal length eyepiee) will reveal fainterstars y inreasing the ontrast etweenthe star images and the sky akground.Heres a tip: When holding high-powerinoulars, position your hands towardthe front of the inoulars, and the viewwill e steadier.

In our example, 50 millimeters is theaperture (size) of eah of the front lenses.The larger this numer, the more light

www.Astronomy.com III

An introductionto binoculars

Binoculars use prisms to bend incoming light several times before it reaches your eyes. Manufac-turers have to position all optical components correctly so that no light is lost. Holley Y. Bakich


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the inoulars ollet, and that makes thetarget righter. Binoulars with front

lenses measuring 50mm ollet morethan twie as muh light as those mea-suring 35mm aross. Astronomiallyspeaking, this is a gain of nearly 0.8 of amagnitude in light-grasp. But larger frontlenses make inoulars igger, heavier,and more expensive.

OpticsThe omponents inside inoulars thatend the light (several times) so theimage appears right-side up are the

prisms. Binoular prisms ome in twoasi designs: roof and Porro (apitalizedeause theyre named for 19th-enturyItalian inventor Ignazio Porro). Roofprisms are lighter and smaller, ut I dontreommend them for astronomy.

Porro prisms are etter for astronomyand are made of either BaK-4 or BK-7glass. BaK-4 prisms (arium rown glass)are the highest quality availale. BK-7prisms (orosiliate glass) are also goodquality, ut image sharpness falls offslightly at the edge of the field of view

ompared to the view through prismsmade of BaK-4.

Most high-quality inoulars are mul-tioated on all optial surfaes. Youllmost often see this referred to as fullymultioated. In the 1950s, manufatur-ers developed oatings that redued lightloss and internal refletions.

Mechanical considerationsCenter-fous inoulars move oth opti-al tues simultaneously. Other models

let you fous eah tue independently.All else eing equal, hoose inoularswith individual fous.

Center-fous units add some mehan-ial ompliation. And even enter-fousinoulars allow you to adjust one tueseparately eause most peoples eyes donot ome to the same fous.

Individual-fous inoulars tend to emore rugged and weatherproof. In eitherase, one you fous your inoulars on anight sky ojet, the fous will e goodfor all other ojets eause all appearinfinitely distant.

Exit pupil

One of the most important terms whendealing with inoulars is exit pupil.This is the diameter of the shaft of lightoming from eah side of the inoularsto your eyes. If you hold the inoulars atarms length and point the front lenses ata right surfae, light, or the sky, youllsee two small disks of light exiting at theeyepiees. These disks are the exit pupils.

The diameter of the exit pupil equalsthe aperture divided y the magnifia-tion. So for our 7x50 inoulars, the exit

pupil diameter would e 50 divided y 7,or roughly 7mm. For astronomy, youwant to maximize this numer eausethe pupils in our eyes dilate in darkness.The wider the shaft of light, the righterthe image will e eause light is hittingmore of your eyes retina.

This loose rule, however, is only trueup to a point. If a inoulars exit pupil is

too large to fit into your eye, you will losesome of the instruments inoming light.

You an measure your pupil size witha gauge availale from some telesopesuppliers. You also may e ale to get onefrom a pharmaeutial ompany or fromyour eye dotor.

Eye reliefEye relief is a funtion of the eyepiee. Itsthe manufaturers reommended dis-tane (for est performane) your eyespupil should e from the eyepiees exitlens. Eye relief generally dereases asmagnifiation inreases. Eye relief lessthan 10mm requires you to position your

eye quite lose to the eyepiee.For eginners, longer eye relief allows

the head more freedom of movement.Also, those who hoose to wear eye-glasses need longer eye relief.

A buyers guideHow should you hoose your first in-oulars? Through the years, Ive advisedmany amateur astronomers to ondut ashort test efore their purhase.

First, pik up the inoulars and shake

them gently. Then twist them gently.Then move the fousing mehanismsseveral times. Move the arrels together,then apart. What youre assessing is qual-ity of workmanship. If you hear looseparts or if theres any play when you twistor move the inoulars, dont uy them.Another thing to onsider at this point isthe weight of the inoulars. If youre

IV Viewing the Night Sky through Binoculars

Actual fields of view through binoculars vary.High-power binoculars generally have smallerfields of view. Photo: Milt Gosney ; illustration: Astronomy: Roen Kelly

If you point your binoculars at a light source, the circles formed by the eyepieces are the exit pupils.For most observers, binoculars with exit pupils measuring 7mm are just right. Michael E. Bakich

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going to e holding them, try to imaginewhat they will feel like at the end of along oserving session.

Look into the front of the inoularsand hek for dirt or other ontaminants.Ignore a small amount of dust on the out-side of the lenses. The inside of the in-oulars, however, should e immaulate.

Hold the inoulars in front of youwith the eyepiees toward you. Pointthem at a right area. Youll see the exitpupils disks of light formed y theeyepiees. They should e round. Iftheyre not round, the optial alignmentof the inoulars is ad and the prismsare not imaging all the light.

Of ourse, you must look through theinoulars. Try to do this outdoors and atnight. Nothing will reveal flaws in thedesign of inoulars etter than starimages. If its impossile to test the unit atnight, or even outdoors, look through adoor or window at distant ojets. Howwell do the inoulars fous? Are ojetslear? If theres any sign of a douleimage, the two arrels are not aligned.Put them down, and walk away.

If youre wearing glasses and if you

plan to oserve with them on an youget your eyes lose enough to the inou-lars to see the entire field of view? Movethe inoulars visually aross a straightline like a phone wire or the horizon, ifpossile. Does the line look distorted? Atiny amount of distortion near the edgesof the field of view is not a ig prolem.

Repeat the tests with several differentinoulars. One you eome morefamiliar with how inoulars ompare,you will e well on your way to purhas-ing an exellent unit.

One fator you may hear aout isfield urvature. This optial flaw ispresent in all inoulars to some extent.Field urvature results from the lensforming a sharp image on a urved sur-fae. When the eyepiees are set to meetthe part of the image that is in fous, say,the enter, you must hange the fous tomake the edges of the image sharp.

The quality of the inoulars isdiretly proportional to the extent thatthe unit minimizes this prolem. An

exellent instrument shows field urva-ture only at the edge of the field. Whenthe entire field of the inoulars is infous, manufaturers all it a flat field. Ifyou use inoulars that have a flat field,you wont soon forget it. Suh units areexpensive, however, eause inoularsthat are flat aross most of the fieldrequire top-noth optis.

Image-stabilized binocularsTo enjoy oth a wide field of view thekind inoulars provide and moder-ately high magnifiation in hand-heldinoulars is to have the est of othworlds. Manufaturers ahieved this yreating image-stailized (IS) inoulars.

IS inoulars use different methods tostailize the image. Some have atteriesthat power a gyrosopi mehanism.Others use a non-powered design that

relies on a gimaled prism. In all designs,you push a utton to engage the stailiza-tion. The results are dramati. For exam-ple, I an now hold inoulars steadyenough to otain good, long looks atJupiters moons.

Giant binocularsGiant inoulars have front lens aper-

tures greater than or equal to aout 4inhes (102mm). Classifying giant in-oulars y size is a it of a gray area,however. Some manufaturers lael thelargest inoulars they sell giant, whihmay e true for them. When most ama-teur astronomers imagine giant inou-lars, however, they think of a pair of shortfoal length 4-inh refrators onnetedtogether or something even larger.

As with smaller models, magnifiationvaries. Some giant inoulars allow you

www.Astronomy.com V

A parallelogram binocularmount allows people of allheights to view the sameobject in the sky justmove the swinging arm up ordown. The arm also rotateshorizontally. A movablecounterweight allows you touse binoculars of differentweights. Holley Y. Bakich


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to hange eyepiees to inrease orderease the magnifiation. No giant in-oulars an e hand-held. They are sim-ply too heavy. If a ase didnt ome withyour giant inoulars, uy one. Dont tryto save money at this point eause youllregret the deision later.

MaintenanceCaring for your inoulars is easy. Mostunits ome with lens aps, eyepiee aps,and a ase. Use them. They will help pro-tet your inoulars from dust and mois-

ture. Dont leave your inoulars exposedto diret sunlight, even if theyre in theirase. Most inoulars (and their ases) arelak or dark-olored and will asor a lotof heat. Heat will ause the arefully plaedelements of inoulars to expand (andlater ontrat) not a good senario.

Cleaning is sensitive only when itinvolves the lenses. If your lenses eomedusty, low them off with ompressed airor rush them with an approved optisrush. Youll find oth of these produts

at any amera store. If you must wipe thelenses, use only lens paper and hange itfrequently, rather than using the samepiee to wipe ak and forth.

The ody of your inoulars also willget dirty. When it does, simply wipe itwith a damp loth.

Binocular mountsFor the steadiest images possile, nothingeats mounting your inoulars to a tri-pod or ustom inoular mount. Smaller,well-mounted inoulars with less mag-nifiation will, after a few minutes ofontinuous use, eat hand-held inou-lars of larger aperture and magnifiation.

The simplest inoular mount is ametal L raket. Attah it to the mount-ing hole on the inoulars enter post.The other end of the L attahes to a am-era tripod. This setup is adequate if theojets youre oserving arent too highin the sky. For ojets near the zenith(the overhead point), tripod-mountedinoulars are unomfortale and insome ases impossile to use.

Another option is to purhase or uilda inoular mount. Most amateur astron-

omers purhase ommerially mademounts. Suh units employ adesign ased on a movaleparallelogram. This arrange-ment keeps the inoularspointed at an ojet over awide range of motion,allowing people of varyingheight to use them.

When seleting a in-oular mount, hoose onethat is sturdier than yourequire. Then you an

upgrade your inoularsto a larger (heavier) modelin the future.

A inoular mount isrugged if, a few seondsafter youve found anojet, the image settlesdown and shows no viration (unlessa strong wind is lowing). If the image isnot stale, your mount may e at fault.

The fault also ould lie with the se-ond piee of equipment youll need: the

tripod to whih the mount attahes. Mostamera tripods are inadequate for thispurpose. They simply are not roustenough to handle the weight of the in-oulars plus the weight of the mount.Balane also ould e a prolem. If youhave a tripod, y all means try it. Youllknow immediately if its up to the task.

A tripod an fail in more ways than yeing flimsy. Maye your sturdy tripod,even at full extension, is not high enoughto allow you to stand under your inou-lars and view ojets near the zenith.

To the skyNow that you have the akground aout

the numers, features, and funtions ofinoulars, its time to head outside. Andwho ould e a etter guide thanAstron-omys own Phil Harrington? His olumn,Phil Harringtons Binoular Universe, isa popular feature in eah months issue.

Weve seleted some of the materialfrom his olumns for the following year-through-inoulars roundup. All youllneed is this guide, inoulars, and a learsky. Although a dark sky eats one thatslight-polluted, youll see muh of what

Phil desries even from uran settings.

VI Viewing the Night Sky through Binoculars

Giant binoculars typically have front lenseswith diameters larger than 4 inches (102mm).Many come with their own fork mounts and tri-pods. Astronomy: William Zuback

The Astronomical League recognizes severalbinocular observing clubs. The league awardsthis certificate if you have observed 50 or moredeep-sky objects out of the 109 on CharlesMessiers list. Michael E. Bakich


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M76

Alpha PerseiAssociation

M34

NGC 884

NGC 869

Algol

16

N

PERSEUS

ANDROMEDA

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JANUARY

A hero for the agesCassiopeia the Queen and her daughter,Andromeda the Priness, play pivotalroles in one of the skys most famous

myths: the legend of Andromeda andCetus. The story goes that Poseidon,Greek god of the sea, punished Cassio-peia for her onstant ragging y kidnap-ping Andromeda and haining her to arok y the sea. There, Poseidon sum-moned his viious sea monster, Cetus, todevour her.

Just as it looked as though all was lost,our storys hero, Perseus, swooped out ofthe sky on the ak of Pegasus the FlyingHorse and saved Andromeda. Five ofthese figures eame onstellations in the

fall sky: Cassiopeia, Andromeda, Cetus,Perseus, and Pegasus.

Perseus the Hero looks like two jaggedars of stars urving away from the Wpattern of Cassiopeia. Perseus righteststar, Mirfak (Alpha [] Persei), lies aouttwo-thirds of the way along a line thatstrethes from Pegasus in the northwestto the right star Capella in Auriga. Mir-fak shines at magnitude 1.8.

Through inoulars, Mirfak appearssurrounded y dozens of fainter stars

sattered in small lumps and patterns.While most of the stars appear whiteor lue-white, a few show slight tingesof yellow or orange. Searh for theorange star Sigma () Persei, one of

three suns forming a small trianglesouth of Mirfak. Also, look for twowhitish doule stars to Mirfaks north.

Together, the stars gathered into thisfootall-shaped area form the Alpha Per-sei Assoiation. A stellar assoiation on-tains mostly hot lue-white and whitestars, like many of the skys open starlusters. Typially, however, the stars inan assoiation gather more loosely thanthose in open lusters.

The Alpha Persei group ongregatearound Mirfak. In the ase of this group,some 50 stars are ound y their mutual ut weak gravitational field.

In Perseus, youll find two wonderfulopen star lusters that appear as twooverlapping irles on the star hart tothe upper right. Their laels, NGC 869and NGC 884, orrespond to their entrynumers in the New General Catalogue.You might also know them y their om-ined nikname, the Doule Cluster.

Even from suuran skies, yourunaided eyes an spot the Doule Clusteras a small, faint smudge of light etweenPerseus and Cassiopeia. Find themthrough your inoulars y extending aline from Gamma () Cassiopeiae, theenter star of the W, through Delta ()Cas and ontinuing east.

If you maintain a straight ourse,youll see oth lusters as two tiny knotsof stars. The one loser to Cassiopeia,NGC 869, appears more densely paked.Most of the stars look either white or

lue-white, ut you might notie a fewyellow and orange stars as well. To makesutle star olors stand out more vividly,defous your inoulars slightly.

Finally, lets take aim at open lusterM34. Youll find it aout halfway etweenthe stars Almah (Gamma Andromedae)and Algol (Beta [] Persei). A great targetfor inoulars, M34 overs an area aslarge as the Full Moon. Look for therightest of its roughly 100 stars withinthe glow of fainter, unresolved suns.

FEBRUARY

The Hunter becomesthe huntedOften, a student will ome up to meefore the semesters first astronomy lass

and ask, So, whats this lass all aout?My answer? Orion!I usually get a perplexed look ak,

ut the fat is that I an ondense muhof the semester into that single onstella-tion. Orion is a mine of wonders; thisgreat onstellation emraes almost everyvariety of interesting phenomena that theheavens ontain, aording to Garrett P.Serviss (18511929) in his 1888 ookAstronomy with an Opera Glass.

If you want to see star irth in ation,look toward the middle star of Orions

sword. That star is not a single sun,ut rather a glowing loud known as theOrion Neula (M42), one of the skysusiest delivery rooms.

M42 is just the tip of a neulous ie-erg that engulfs nearly the entire on-stellation. As this giant loud sprawlsfrom northwest to southeast, it hasdeposited pokets of newly formed starlusters in its wake. To the north, theloud has parted to reveal several easy-to-find open star lusters.

www.Astronomy.com VII

Interchangeable eyepieces make these binoc-ulars adaptable to a variety of astronomical tar-gets. Astronomy: William Zuback

When you point your binoculars toward the

constellation Perseus, you wont miss the Dou-ble Cluster (NGC 869 and NGC 884). Dont stopthere, however. Check out open cluster M34.Astronomy: Richard Talcott and Roen Kelly


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65

43

21

1

2

N

ORION

Betelgeuse

Collinder 65

Collinder 69

Collinder 70

Rigel

W

2

M78

M42

M37

M36

M38

NCapella

26

16

5

14

18

AURIGA

2

All three of Orions rilliant eltstars, along with another hundred or sofainter suns, elong to the open star lus-ter known as Collinder 70. Swedishastronomer Per Collinder (18901974)first identified this ojet as a luster inhis 1931 atalog.

Many of the 471 open lusters thatCollinder inluded are too large and

sparse to appreiate through most tele-sopes, ut theyre perfet for inoulars.Most of Collinder 70s stars shine

righter than 9th magnitude, withinrange of 50mm inoulars from suur-an skies. Overall, Orions three elt starsmark the width of Collinder 70. A dis-tintive S-shaped hain of 11 faint starssnakes from Mintaka, the elts westernstar, to Alnilam at its enter.

Follow the trail of star formationnorth to Orions triangular head. The tri-angles top star (Lamda [] Orionis) and

several dozen fainter suns within aout1 all elong to another open luster, Col-linder 69. Most inoulars revealetween 15 and 20 stars ranging inrightness from 5th to 9th magnitude.

A third Collinder luster, Collinder 65,spills into adjaent Taurus. By adding afew non-luster stars to the east and north,I imagine this luster as a spear that Orionis aout to heave at the Bull. Orionsspear measures aout 8 tip to tip, whihmakes it perfet for 7x inoulars.

MARCH

Visit the CharioteerHead outside some Marh evening, andlook overhead. If you live in mid-northernlatitudes, youll find a lone eaon restingnear the zenith the point in the skystraight overhead as the sky darkens.Capella lies in Auriga the Charioteer.

Traing ak to anient Rome, thename Capella translates to mother goat,a referene to the position it holds in theCharioteers piture. Near Capella liethree stars that represent the goats kids three 3rd-magnitude stars in the shape

of an isoseles triangle. They glisteneautifully through inoulars. Twoshine pure white, while the third, Zeta ()Aurigae, appears orange.

Hop a little more than a inoular fieldsouth of, or elow, the triangle to see aneat little pattern of five faint stars. Fourform a parallelogram, while the fifth liesjust elow. This isnt a star luster, ut anasterism one of those fun shapes youump into every now and again.

Given Marhs windy days, the pattern

reminds me of a kite with a tail whippingaout. With your unaided eyes from adark site, you might see the kites olongglow west of the onstellations enter.

Look north of the ox kite for a dimglow among the stars. Thats M38, one ofAurigas three Messier open lusters.Dont e surprised if you ant see M38 atfirst. This luster an e tough to pik outfrom among the surrounding stars.

While looking for M38, you mightnotie M36, a seond fuzzy glow snug-gled etween two faint field stars aouthalf a inoular field to the east. M36 is asmaller and more ondensed open lusterthan M38, so you should e ale to spotit more easily.

If you have good eyes and 70mm orlarger inoulars, you might see a fewfaint stars peering ak at you. Telesopes

reveal the lusters rightest stars forminga rooked Y pattern.The rightest Messier open luster in

Auriga, the Salt-and-Pepper Cluster(M37), rests aout a inoular field eastof M36. Beause its rightest stars shineat only 9th magnitude, M37 appears as afaint, misty path through inoulars.

APRIL

Two crabby clustersIf I asked you to name your favoritespringtime onstellation, odds are youwouldnt mention Caner the Cra. Afterall, Caner isnt muh to look at, and justfinding it is diffiult enough its right-est stars shine at 4th magnitude. Thatmakes this one tough ra to ath.

Look midway etween the right starsCastor and Pollux (Alpha [] and Beta[] Geminorum) in Gemini and Regulus(Alpha Leonis) in Leo. There, youll findCaners four-star shelled ody.

VIII Viewing the Night Sky through Binoculars

Orion is one of the skys brightest and most rec-ognized constellations. It contains numerousbinocular targets like the Orion Nebula (M42)

and three large Collinder clusters: numbers 65,69, and 70. Astronomy: Richard Talcott and Roen Kelly

When you finish watching Capella (Alpha []Aurigae) sparkle through your binoculars, aimthem at open clusters M36, the Salt-and-PepperCluster (M37), and M38. Astronomy: Richard Talcott and Roen Kelly

The Salt-and-Pepper Cluster (M37) in Auriga isone of the skys brightest open clusters. Throughbinoculars, youll see a misty patch composed ofseveral hundred stars. Neil Fleming


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Beehive Cluster

(M44)

M67

Acubens

CANCER

2

N

Look inside the Cras ody with yourinoulars, and youll notie it frames aswarm of faint stars the Beehive Clus-ter (M44). One of historys first pulishedoservers, the Greek philosopher Aratusdisovered this luster in 260 b.c.

When I look at the Beehive throughmy 10x50 inoulars, I see the shape of aright triangle. Of the 36 luster stars I anount, most shine etween magnitudes 7and 9. Many form interesting pairs orpatterns with their neighors.

For instane maye eause Aprilsignals the start of aseall season I seeM44s five rightest stars grouped as ahome plate just south of the lusters en-

ter. A loser look at the star marking theplates pointy tip reveals it as a triangle ofstars. Multiple-star fans know this groupas Burnham 584. Before you try to spotthe three stars, rae your inoulars. Aseond onspiuous pairing of stars alsostands out just north of the lusters enter.

To find Caners seond luster, traeits southeastern leg away from the Crastrapezoidal ody to the 4th-magnitudestar Auens (Alpha Canri). Centeryour view on Auens, then shift your

attention to the inoular fields westernhalf. You should spot the dim glow ofM67. You might even pik out a few faintstars shining within M67s haze.

MAY

The Big DipperRememer the ry of exitement whenyou reognized the Big Dipper for thefirst time? Lets first examine eah of thefour stars that make up the owl: Duhe(Alpha [] Ursae Majoris), Merak (Beta[] UMa), Pheda (Gamma []), andMegrez (Delta []). All shine nearly

white, exept for Duhe at the owlsnorthwest orner, whih radiates anorangish glow.

Using your imagination, draw a linefrom Pheda, at the owls southeasternorner, to Duhe. Extend that line anequal distane to the northwest until youome to a small right triangle of stars.The star marking the right angle itself is24 Ursae Majoris, while most star hartsdont name the other stars.

If you look arefully, you just mightspot a faint lur to the triangles south-

east. Thats no star, ut rather Bodes Gal-axy (M81). Admittedly, finding M81 anprove daunting at first. Through 7x35inoulars, the galaxys oval shapeappears small and dim. Larger inoularsinrease the ontrast etween the galaxysright enter and the dimmer surround-ing halo, although inoulars wontresolve the spiral arms.

Look just north of M81, and try tomake out a dimmer splinter of grayishlight. If you do, youve found the Cigar

Galaxy (M82). Even 7x35 inoularsreveal this galaxys famous shape, pro-vided your sky is dark. Unlike M81, how-ever, whih shows a righter ore, M82appears uniformly dim from end to end.

M81 and M82 form a striking galaxypair. Other galaxies elong to the M81Group, ut we an see only one NGC2403 through inoulars. It lies a gooddistane away, aross the order withinthe faint onstellation Camelopardalis.

Hunting down NGC 2403 an etough, ut heres how I do it. Start atM81, and move aout 1 inoular fieldsouthwest to a slender triangle formed y5th-magnitude stars Rho (), Sigma1 (1),and Sigma2 (2) Ursae Majoris. This dis-tintive triangle points toward the west-northwest, right at a lone magnitude 5star aout a field of view away. Fromthere, jog another inoular field south-west to a larger right triangle of three6th-magnitude stars. Our target lies half-way etween the triangles right angle and

its southern orner.Next, look at the end of the Big Dip-

pers handle. There, youll find the starAlor (80 Ursae Majoris). With Mizar(Zeta [] UMa), it makes a fun naked-eyetest and an easy target for even the small-est inoulars. Mizar shines at 2nd mag-nitude, while Alor glows at 4th.

From Mizar, aim toward Alkaid (Eta[] Ursae Majoris), the star at the end ofthe Dippers handle. Look half a inou-lar field to Alkaids west-southwest for a

www.Astronomy.com IX

Two open clusters in Cancer beckon your binocu-lars. The brighter one is the Beehive Cluster (M44).Its an easy naked-eye object from a dark site.M67, on the other hand, will test your eyes if youview it through small binoculars. Astronomy: Roen Kelly

Sharp-eyed observers with high-quality binoculars will have no trouble spotting Bodes Galaxy(M81) and the Cigar Galaxy (M82) in the same field of view from a dark site. Adam Block/NOAO/AURA/NSF

M82

M81


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N

Arcturus

Mel 111

35

M3

2411

BOTESCANES VENATICI

COMA BERENICES

2

6

URSA

MAJOR

M81

NGC 2403M82

Dubhe

Merak

Phecda

Megrez

23

5

N

Mizar

Alcor

M101

Alioth

M51

Alkaid

5

N

U R S A M A J O R

4th-magnitude star, and then move anequal distane farther south to a penta-gon of dimmer suns. If you look arefullyjust inside the pentagons eastern orner,you might spot a dim glow. Thats theeautiful Whirlpool Galaxy (M51).

Through 70mm and larger inoulars,you might notie M51 appears lopsided.You arent looking at just one galaxy, uttwo. Charles Messier missed M51s om-

panion, so you wont find it in his atalog.We know it today as NGC 5195. NGC5195 glows at aout 10th magnitude.

JUNE

Star clusters close-upLets kik off June with a visit to theright star Arturus (Alpha [] Botis).We an use Arturus to find other ojetsof interest in the area.

For instane, if you move away fromArturus toward the west (down and tothe right in the evening sky in the North-ern Hemisphere) aout 4 inoularfields, you ome to a dense group of stars.You might even see it as a hazy glow withyour eyes alone. Thats the Coma Bereni-es star luster also known as Melotte(Mel) 111 one of my favorite inoularstar lusters. This olletion of aouteighty 5th- to 10th-magnitude stars is

perfet for 7x to 10x inoulars eauseit spans 5 10 Full Moon-widths.The luster is not espeially large.

Instead, it looks ig eause it lies neary.Today, we know the Coma star luster isaout 250 light-years away, making it theopen luster third-losest to us.

The rightest stars in the Coma starluster resemle the lower-ase Greekletter Lamda (); or, if youre viewingfrom south of the equator, Gamma ().Most shine white, while some show hintsof yellow or orange. For instane, the star

at the top of the Lamda, 15 Comae, isanother type K star, like Arturus.

Look for 17 Comae, a prominent dou-le star just east of the lusters enter.Even opera glasses show 17 Comaes 5th-magnitude primary and its magnitude 7ompanion easily.

Now, look for the star Cor Caroli(Alpha [] Canum Venatiorum), thelone star visile to the naked eye justunder (south of) the end of the Dippershandle. Aim your inoulars halfway

etween Arturus and Cor Caroli, andthen look for a right triangle of three dimstars that points toward the southeast.

Spot it? If so, look at the star markingthe right angle. If you look arefully,youll notie its not a perfet point oflight. Instead, it looks like a tiny, fuzzystar lo. Youre atually seeing a dis-tant group of more than 100,000 stars a gloular luster alled M3. To me, itlooks like a distant all of elestial otton.

JULY

A tails taleThe onstellation Sorpius is a rare reed.Why? Beause Sorpius atually lookslike what its supposed to represent.

The right orange star Antares (Alpha[] Sorpii) marks the Sorpions heart.Immersed in the glow of the Milky Way,Antares makes a jumping-off point tosearh for many hidden treasures. Lets

egin with gloular luster M4. Its just ahalf degree to the west of Antares. Lookfor a dim, round glow that appears fuzzy.

At 7,200 light-years away, M4 is rela-tively lose to Earth for a gloular luster.This makes it appear igger than mostand easy to identify through 6x inou-lars. But eause M4 has loose struture,its lak of a ondensed enter an on-found oservers in light polluted areas.

Sorpius houses a seond Messiergloular luster that proves hallenging

X Viewing the Night Sky through Binoculars

Botes contains Arcturus (Alpha [] Botis), the skys fourth-brightest star. Look northwest of it for glob-ular cluster M3, then west again for the Coma Berenices star cluster (Mel 111). Astronomy: Richard Talcott and Roen Kelly

Ursa Major the Great Bear ranks as the third-largest constellation. A good test for your sky,your binoculars, and your eyes is to try to spottwo deep-sky objects: Bodes Galaxy (M81) andthe Cigar Galaxy (M82).

Search the eastern part of Ursa Major for spiralgalaxy M101. If your binoculars reveal it, youllhave no problem finding the Whirlpool Galaxy

(M51) in nearby Canes Venatici. Astronomy: Roen Kelly


10/14

44

45

M19

M62M6

M7

M4

M80

2

12

1 2

12

N

Antares

Shaula

SCORPIUSSCORPIUS

LUPUSLUPUS

OPHIUCHUSOPHIUCHUS

2

through inoulars: M80. This lusterrests halfway etween Antares and Graf-fias (Beta [] Sorpii). Although its star-like ore is typial, M80 is tiny omparedto M4, so identifying it from surroundingstars an e diffiult.

Now, plae Antares at the westernedge of the field and look on the oppositeside for a lose-set pair of 5th-magnitudestars lying aross the invisile order inOphiuhus. The gloular luster M19 liesjust a degree to their south. Looking alittle larger and slightly righter thanM80, M19 should reveal itself as a fuzzystar through 7x inoulars.

While viewing M19 through 10x50

inoulars, Jim Elliott of Lee County,North Carolina, oserved an unusual arof three optial doule stars urvingaround M19 to the northeast. I all thisassemly of stars (whih inludes 24, 26,and 36 Ophiuhi and SAO 184892,185020, and 185033) the Dish o Douleseause they remind me of a satellitedish, with M19 at the fous.

Next, look for the fainter gloularluster M62 aout half a field to thesouth. M62 appears featureless through

8x42 inoulars; however, my 15x70 in-oulars reveal a righter, stellar ore.

Next, proeed southward along theSorpions rooked ody to the tip of itsstinger, marked y the stars Shaula(Lamda [] So) and Lesath (Upsilon[] So). If you plae the pair on the ot-tom edge of your inoulars field, to thenorth and northeast you should see twodistint lumps of stars (aove and to theleft): M6 and M7, respetively.

The rightest stars in M6 form a ret-angle, although more inventive eyes animagine a utterflys outline among thestars. Look for two wings outstrethedfrom the insets ody. The utterflyappears to e headed southeast.

M7 is larger and righter than M6.

Even through the smallest inoulars,M7 will urst into a striking assortmentof stars overing an area larger than theFull Moon. Several of its roughly 80 starsshow sutle hues of yellow and lue, withthe rightest a yellow eaon lying loseto the groups enter.

AUGUST

Im a little teapot ...

In August, a elestial teapot gets allsteamed up and pours out into the heav-

ens. Of ourse, I am referring to the on-stellation Sagittarius. Anient eyesstrained to see a entaur aiming a owand arrow at the star Antares, the Sorpi-ons heart. Todays stargazers find a teapotamong the patterns eight rightest stars.

Lets egin with the finest right ne-ula in the summer sky: the Lagoon Ne-ula (M8). The Lagoon lies aout ainoular field west of Kaus Borealis(Lamda [] Sagittarii), at the tip of theteapots top. Loate the star in your in-oulars, and then look toward the west-ern edge of the field. You should spotseveral stars enmeshed in a glowingloud. Many of those stars elong to theopen luster NGC 6530, whih is formingwithin the Lagoon.

Careful examination should show thatthe Lagoon isnt uniform, ut insteadlooks lopsided. The western side glowsrighter and appears more ulous thanthe eastern half. A lane or lagoon of osuring dust divides the neula.

Now, without moving your inoulars,look less than half a field north of theLagoon to find a small diamond-shapedpattern of stars. The southernmost star inthe diamond atually is surrounded y aseond, muh smaller, path of neulos-ity known as the Trifid Neula (M20).

Sagittarius offers five gloular lustersto oserve through inoulars. Throughtelesopes, these lusters look likemounds of sugar poured onto a velvetylak akground.

The sweetest gloular of the unh isM22. Look toward Kaus Borealis at thetop of the teapots lid, and then san justto the east. M22 is the lurry, round disknext to an isoseles triangle of faint stars.

Now, pan just to the northwest ofKaus Borealis for a seond, muh

www.Astronomy.com XI

Ptolemys Cluster (M7) is an easy binocular tar-get. To find it, just look to the left of Scorpiusthe Scorpions stinger. Adam Block/NOAO/AURA/NSF

Search near Scorpius stinger for open clusters M6 and M7. Then point your binoculars toward bril-liant Antares (Alpha [] Scorpii), and find globular clusters M4 and M80. Astronomy: Richard Talcott and Roen Kelly


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M69M70

M54

M21

M20

M8M22

M28

1

2

12

SAGITTARIUSSAGITTARIUS

N

2

tougher, gloe of stars. Through inou-lars, M28 looks like a small smudgeetween Kaus Borealis and a dim field

star. Its muh harder to find than M22,ut take your time and M28 eventuallywill surrender to your hunt.

Our final three gloulars lie along theottom of the teapot, ut e forewarned,they are daunting tests through inou-lars. Use a pair of fainter stars east of thestar Kaus Australis (Epsilon [] Sagittarii)as a guide. M69 lies just to their north,while M70 is to their east. M69 and M70eah shine at only 8th magnitude, so waitfor a lear, haze-free sky efore trying

your luk. Under etter than averageonditions, I an see eah as a faint,slightly fuzzy star through my 10x50s.

The third gloular in this area, M54, iseasiest to find y starting at Asella (Zeta[] Sagittarii), the teapots lower-left star.M54 lies diretly to its west, just south ofa triangle of dim stars. Like its two om-patriots, M54 will impress you as a tiny,lurry point of light highlighted y aslightly righter enter.

SEPTEMBER

Strum the HarpThe rilliant stellar sapphire Vega (Alpha[] Lyrae) sparkles high in the west thismonth. Famous as the fifth-rightest starin the night sky, Vegas dazzling glowpunhes through even severe light pollu-tion. You simply ant miss it!

Lyra, Vegas onstellation, symolizesthe harp owned y the mythologialmusiian Orpheus. Vega marks part of

the harps handle, while a parallelogramof four fainter stars frame its ody.

Sheliak (Beta [] Lyrae), at the paral-lelograms southwestern orner, is atu-ally an elipsing inary that is perfet forinoular study. In just under 13 days, anunseen ompanion star auses Sheliak torighten from magnitude 3.3 to 4.3.Compare Sheliaks rightness to that ofneary stars that do not vary.

The most photographed planetaryneula of all, the Ring Neula (M57), liesalong the southern edge of the parallelo-gram. To spot it, look midway etweenSheliak and Sulaphat (Gamma [] Lyrae)for three faint stars that reate a tiny right

triangle. The star at the right angle isatually the Ring. Although it takes atleast 50x to make out its smoke-ringshape, Ive seen M57 as a faint starlikepoint through 7x35 inoulars.

Now, san southeast of Sulaphattoward the star Alireo (Beta Cygni), andpause aout halfway in etween. There,youll find a onspiuous asterism shapedlike the numer 7. If you look just to the7s southeast, you should spot a smudgethat doesnt quite look like a star. Thats

gloular luster M56.Even the smallest poket inoulars,however, will reveal Delta () Lyrae, atthe Harps northeastern orner, as twolose-set stars. In fat, some sharp-eyedstargazers dont need any optial aid at allto see them. The pairs righter star, mag-nitude 4.3 Delta2, looks orangish, whilemagnitude 5.6 Delta1 is luish-white. Thetwo Delta stars elong to a sattered openluster niknamed the Delta Lyrae Clus-ter and ataloged as Stephenson 1.

Fifteen stars elong to Stephenson 1,

with most too faint for inoulars.Although oth Deltas elong to this lus-ter, studies suggest that Delta1 lies aout1,200 light-years away, while Delta2 restsaout 200 light-years loser to us alassi example of an optial inary star.

The next stop on our tour is Epsilon() Lyrae, just to Vegas northeast.Through inoulars, Epsilon easilyresolves into two points of light. Thenorthernmost of the pair is laeled Epsi-lon1, while the other is Epsilon2.

Many oservers also know this systemas the Doule Doule eause Epsilon1and Epsilon2 are eah lose-set pairs ofstars. Unfortunately, it takes at least 80xto see all four stars, so you wont spot thepairs through inoulars.

Under dark skies, san southeastwarda inoular field diameter to the 3rd-magnitude star Delta Aquilae, and thenan equal distane farther southeastwardto 3rd-magnitude Lamda () Aquilae.Lamda and two fainter adjaent starsform an ar that hooks ounterlokwise,diretly toward the Sutum Star Cloud.

Sutum the Shield is a faint onstella-tion thats diffiult to pik out. But

through inoulars, the Sutum StarCloud stands out as one of the MilkyWays rihest regions.

As you look around, notie severalpokets where the star density inreases.The Wild Duk Cluster (M11) stands outas a dazzling sight. You an find it as aright smudge of starlight just to the westof the Eagles tail-feather stars.

Beause most of M11s stars are toofaint to see through inoulars, theylend into a small round mist of starlight,

XII Viewing the Night Sky through Binoculars

Sagittarius the Archer resembles a stellar tea-pot. It lies in the rich star fields of the Milky Way,so youll find lots of binocular treats here. Youcan spot no less than five globular clusters inthis area. Astronomy: Richard Talcott and Roen Kelly

Not everything in the sky appears bright. Scanthe Milky Way in Aquila the Eagle for two darknebulae that form the letter E Barnard 142and Barnard 143. Michael Stecker


12/14

M57

M56

N

Vega

T

LYRA

CYGNUS

2

59

5

11

M26

M11

N

12

Altair

AQUILA

SCUTUM

SAGITTARIUS2

exept for a lone 8th-magnitude sun thatshines aove the fray.

A seond smudge of ondensed star-

light lies aout half a inoular fieldsouthwest of M11. Look for it southwestof a slender right triangle of stars formedy Alpha, Delta, and Epsilon Suti.

M26 inludes aout 30 stars. Noneshines righter than 10th magnitude sothe luster is not right enough for you to

see through most inoulars. Instead,M26s light produes a hazy glow over-ing aout a quarter of a degree, or aouthalf of the Moons diameter in our sky.

OCTOBER

The Swan delightsAlthough youd never know from lookingat it asually, Dene (Alpha [] Cygni),marking the tail feathers of Cygnus theSwan, is one of the most luminous starsin the entire sky. Even though it appearsfainter than Vega and Altair, Dene atu-ally emits muh more energy than either.

Cygnus marks one of my favorite in-oular playgrounds. Even from my mod-erately light-polluted suuran akyard,I an sit ak, peer through my 10x50

inoulars, and trae the gentle glow ofthe Milky Way from Dene southward tothe star Alireo (Beta [] Cygni), whihmarks the irds eak.

Small telesopes reveal Alireo as ashowpiee doule star with a magnitude3 golden primary star aompanied y a5th-magnitude sapphire-lue ompan-ion. Their olors dont show up as well,ut youll spot oth stars through steadilyheld 10x50 inoulars.

If doule stars interest you, then stopy Omiron () Cygni, one of the finest

doules through inoulars. Look for it5 or aout two-thirds of a inoularfield northwest of Dene. This systemis another olorful pair: a 4th-magnitudeorange star aompanies a magnitude 5luish sun. Their olors stand out even intheir rih neighorhood.

Up for a ouple of hallenges? Good.Lets egin with the open star lusterM39, found along the lane of the MilkyWay aout 9 or approximately 1.5inoular fields northeast of Dene.

www.Astronomy.com XIII

The Wild Duck Cluster (M11) lies just off the tail stars of Aquila the Eagle in the small, faint constel-lation Scutum the Shield. M11 stands out well even in a rich Milky Way star field. Michael Stecker

High in the Northern Hemispheres summer sky,youll see the small constellation Lyra the Harp.Trying to spot the famous planetary nebula theRing Nebula (M57) through binoculars is a realchallenge. Astronomy: Richard Talcott and Roen Kelly

With binoculars, scan the Milky Way southwest of Aquila the Eagle. Here, the Scutum Star Cloud pro-vides two treats: the Wild Duck Cluster (M11) and another open cluster, M26. Astronomy: Richard Talcott and Roen Kelly


13/14

NGC 663

M103

NGC 457

M52

N

CASSIOPEIA

2

NGC 7000

M29

Veil Nebula

1N

Albireo

Deneb

CYGNUS

VULPECULA

LYRA

2

To find M39, san from Dene to asmall arrowhead of stars just to thenortheast. Follow the arrowheads aim toa string of six faint stars that ontinues tothe east-northeast. M39 lies to the east ofthe sixth (easternmost) star in that line.Through most inoulars, M39 will looklike a tiny triangular grouping of aouttwo dozen faint points. Whenever I am

fortunate enough to view from a darkloation, M39 appears suspended in frontof a lanket of faint stardust.

Lets finish with the North AmeriaNeula (NGC 7000). Although spottingthis elestial ontinent is tough, its easierto see through inoulars than throughthe narrow fields of most telesopes. Takeaim at Dene, and then look aout 3(half a inoular field) to its east.

No luk? Heres a hint. Look for theEast Coast, from the Carolinas to Flor-ida, and the Gulf of Mexio. These are

the neulas easiest parts to see, thanks tothe darkness of the Atlanti Oeanformed y a separate dark neula silhou-etted in the foreground. The WestCoast is more diffiult to distinguish.

NOVEMBER

In the Queens courtAfter the Big Dipper and Orion, the mostreognizale star pattern visile from the

Northern Hemisphere may e the W ofCassiopeia, the mythial Queen of Ethio-pia. During Novemer, Cassiopeia rideshigh aove Polaris and looks resplendentin the Milky Ways gentle glow.

One of my favorite open lusters inCassiopeia is M52. To find it, draw a linefrom Shedar (Alpha [] Cassiopeiae) toCaph (Beta [] Cas), the westernmost

stars in the W, and ontinue it an equaldistane to the northwest. There, youshould spot a slender, four-star diamondpattern. M52 lies to the diamonds south.

Although aout 200 stars all M52home, few are right enough to rak theinoular arrier; the rest lend into alittle loud of misty starlight.

One youve enjoyed M52, return tothe star Caph in the Cassiopeia W. Canyou spot three pairs of stars just to itssouth-southwest? Although none of themis a true inary system, eah pair forms

the orner of a slim triangular asterismthat reminds me of a skinny hang glider.The rightest star in the asterism, Rho() Cassiopeiae, is one of the two at thegliders nose, while 5th-magnitude Sigma() Cas the righter of the two stars is at the end of the southern wing.

You might even spot a faint stain onthe leading edge of the gliders southernwing. Thats NGC 7789, a distant openluster. Dont expet to see a lot of starsthrough inoulars. Instead, NGC 7789

looks like a faint round glow with one ortwo elusive points shining through.

One of Cassiopeias fine sights liesnear the star Zeta () Cas. Through in-oulars, 4th-magnitude Zetas distintaquamarine hue ontrasts niely againstShedars orangish tint.

Zeta lies at the end of a semiirularasterism of seven fainter stars. Together,

they resemle a akward 3 or a minia-ture Corona Borealis. Beause olderdepitions of the onstellation show Zetarepresenting the Queens head, Cassio-peias rown seems an appropriate namefor this little asterism.

XIV Viewing the Night Sky through Binoculars

The North America Nebula (NGC 7000) residesin Cygnus the Swan. Find it southeast of thebright star Deneb, just west of Xi () Cygni. The

easiest sections to see are the eastern seaboardand the Gulf of Mexico. Augie Orlandi The North America Nebula (NGC 7000) in Cygnus can be tough to spot through binoculars. Observeunder a dark sky, scan east of Deneb (Alpha [] Cygni), and be patient. Astronomy: Richard Talcott and Roen Kelly

Cassiopeia the Queen boasts many open clus-ters youll enjoy observing through binoculars.Be sure to target open clusters M52 and the OwlCluster (NGC 457). Astronomy: Richard Talcott and Roen Kelly


14/14

M31

M32

And I

NGC 205

N

51

59

6

39

TRIANGULUM

ANDROMEDA

2

Lets go deeper into the onstellationy following the zigzag path along theCassiopeia five-star W to Ruhah (Delta[] Cas), at its lower-left orner. Aim half

a inoular field to the southwest ofRuhah toward 5th-magnitude Phi ()Cas. Youll see a seond fainter star just toPhis southwest as well as a tiny smear ofdim starlight to the north. Together, theyform the Owl Cluster (NGC 457). Thetwo rightest stars mark the owls eyes,while the fainter suns outline its odyand outstrethed wings.

Next, lets stop y open luster M103,loated on the other side of Ruhah. My10x50s show this group as a small trian-

gular path of starlight nestled in a prettyMilky Way field. I an make out four orfive separate stars here. The rest of its 170memers pool their faint light to reatewhat looks like a tiny arrowhead. Othersthink M103 resemles a hand-held fan.

DECEMBER

Visit the Andromeda Galaxyand the PleiadesWelome to the end of the year and a

great inoular target: the AndromedaGalaxy (M31). To find M31, first loatethe star Alpheratz (Alpha [] Androme-dae). From Alpheratz, slide aout oneinoular field northeast, to the faint starDelta () And, then another field farthernortheast to Mirah (Beta [] And). Takea sharp right turn northwestward, firststopping at Mu () Andromedae andthen onward to Nu () Andromedae.

Finally, look just northwest of Nu for adim, elongated lur. It may not look like

muh at first, ut youve found theAndromeda Galaxy, the omined lightof several hundred illion suns.

Binoulars show it as a road ovalsmudge of grayish light highlighted y aprominent ore. From a dark rural loa-tion, you an see the full span of theextensive spiral-arm disk. M31 reahesout as far as 5 thats as wide as 10 FullMoons staked side y side!

You an spot M31s two largest satel-lite galaxies through inoulars, althougheah will push your limits. The smallerand righter of the pair, M32, is a starlikepath due south of M31s ore. The se-ond ompanion, NGC 205, is larger,

fainter, and more diffiult to oserve.Look for it to the north of M31s ore,aout twie as far as M32.

Next, we ome to my favorite inou-lar open star luster: the Pleiades (M45).Is there any ojet more eautiful thanthe sapphire-lue stars of the Seven Sis-ters glistening through inoulars?

The Pleiades holds many doule andmultiple stars. For instane, Atlas andPleione form a wide pair in inoulars,while Asterope is a pair of easily o-

served 6th-magnitude stars.

On a lear evening, you may see a hintof faint interstellar dust surroundingsome of the righter stars. The rightest

portion of the Pleiades neulosity, NGC1435, enirles Merope and extendssouth. Many stargazers are fooled intothinking theyve seen the neulositywhen they notie a right glow aroundeah of the rightest Pleiades.

What they are really seeing is starlightsattering inside their inoulars. Tomake sure youre glimpsing the realthing, hek the neary Hyades open starluster. If you also see neulosity there,where there is none, then your inoulars

are fogged or need leaning.

Open cluster M52 in Cassiopeia looks great onits own, but be sure to scan the surroundingarea for other nice star patterns. Anthony Ayiomamitis

The Pleiades (M45) is one of the skys finest bin-ocular targets. Youll spot several dozen starshere and, if your sky is dark, perhaps even theMerope Nebula (NGC 1435). Chris Schur

Many observers list the Andromeda Galaxy (M31) as their favorite deep-sky object. It ranks as thebrightest galaxy north of the celestial equator. You can see it and two of its fainter companiongalaxies M32 and NGC 205 through binoculars from a dark site. Astronomy: Richard Talcott and Roen Kelly

Viewing Thenight Skyt HroughBinoculars

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